Method of forming a semiconductor device and structure therefor

ABSTRACT

In one embodiment, a control circuit for a linear vibration motor may be configured to drive the linear vibration motor to vibrate using a closed loop run mode or an open loop run mode, and may be configured to control the linear vibration motor to stop vibrating using an anti-drive signal wherein the frequency is adjusted to be near to an estimated value of the natural frequency of the linear vibration motor.

PRIORITY CLAIM TO PRIOR PROVISIONAL FILING

This application claims priority to prior filed Provisional ApplicationNo. 62/211,182 entitled “METHOD OF FORMING A SEMICONDUCTOR DEVICE ANDSTRUCTURE THEREFOR” filed on Aug. 28, 2015, and having common inventorTsutomu Murata which is hereby incorporated herein by reference

Cross-Reference to Related Applications

This application is related to an application entitled “METHOD OFFORMING A SEMICONDUCTOR DEVICE AND STRUCTURE THEREFOR” and U.S.application Ser. No. 15/242,786, having a common assignee, and inventorTsutomu Murata which is filed concurrently herewith and which is herebyincorporated herein by reference.

This application is also related to an application entitled “METHOD OFFORMING A SEMICONDUCTOR DEVICE AND STRUCTURE THEREFOR” and U.S.application Ser. No. 15/242,804, having a common assignee, and inventorTsutomu Murata which is filed concurrently herewith and which is herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates, in general, to electronics, and moreparticularly, to semiconductors, structures thereof, and methods offorming semiconductor devices.

In the past, the semiconductor industry utilized various methods andstructures to form semiconductor devices to control linear vibrationmotors. In some cases the circuits would drive the linear vibrationmotor to an excessive extent and may cause the weight of the linearvibration motor in the case of the motor. When the weight the case, itoften caused an audible noise and also may have interrupted theoperation of the linear vibration motor. In some cases, the frequency ofthe drive signal used to drive the linear vibration motor may have beendifferent from the frequency for which the linear vibration motor wasdesigned. This could also undesirable audible noise or in some cases mayreduce the effectiveness or efficiency of operation. In some cases, itmay have taken a longer time than desired to stop the vibration of theLRA. In some applications, the linear vibration motor may have beenvibrating before the control circuit began driving the linear vibrationmotor. Consequently, the resulting vibration may have been ineffectivefor a user.

Accordingly, it is desirable to have a circuit and/or method thatreduces the occurrence of the weight hitting the case, or that drivesthe linear vibration motor a frequency closer to the design frequency ofthe linear vibration motor, or that provides more efficient operation orthat can reduce the time required to stop the LRA or that canaccommodate the linear vibration motor already vibrating.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an example of a portion of anembodiment of a drive control circuit for controlling a linear vibrationmotor (LRA) in accordance with the present invention;

FIG. 2 illustrates in a general manner, a cross-sectional view of anon-limiting example of a linear vibration motor that may be suitablefor use as an LRA for the circuit of FIG. 1 in accordance with thepresent invention;

FIG. 3 is a graph having plots that illustrate some signals that may beformed by the circuit of FIG. 1 in accordance with the presentinvention;

FIG. 4 schematically illustrates an example of a portion of anembodiment of a drive control circuit that may be an alternateembodiment of the circuit of FIG. 1 in accordance with the presentinvention;

FIG. 5 is a graph having plots that illustrate some signals that may beformed by the circuit of FIG. 4 in accordance with the presentinvention;

FIG. 6 schematically illustrates an example of a portion of anembodiment of a circuit that may be an alternate embodiment of a decodercircuit of FIG. 1 or FIG. 4 or FIG. 7 in accordance with the presentinvention;

FIG. 7 schematically illustrates an example of an embodiment of aportion of a drive control circuit may be an alternate embodiment of thedrive control circuit of FIG. 1 or FIG. 4 in accordance with the presentinvention;

FIG. 8 illustrates in a general manner a flow chart that illustrates ina general manner an embodiment of some steps in an embodiment of amethod of operation for the circuit of FIG. 7 in accordance with thepresent invention;

FIG. 9 is a graph having three plots that illustrate some non-limitingexamples of some signals that may be formed during the operation of anembodiment of the circuit of FIG. 7 in accordance with the presentinvention;

FIG. 10 is a graph having plots that illustrate another example of anembodiment of a method that may be formed by the circuit of FIG. 7 inaccordance with the present invention;

FIG. 11 is a graph having plots that illustrate an example of anotherembodiment of a method that might be formed by the circuit of FIG. 7 inaccordance with the present invention;

FIG. 12 schematically illustrates an example of an embodiment of aportion of a drive control circuit that may be an alternate embodimentof any of the circuits of FIG. 1, 4, or 7 in accordance with the presentinvention;

FIG. 13 illustrates in a general manner a flowchart of an example of anembodiment of a method that may be formed by an embodiment of thecircuit of FIG. 12 in accordance with the present invention;

FIG. 14 schematically illustrates an example of an embodiment of blockdiagram of a circuit that may be an alternate embodiment of some of thecircuits of FIG. 12 in accordance with the present invention; and

FIG. 15 illustrates an enlarged plan view of an example of a portion ofan embodiment of a semiconductor device that may include at least one ofthe circuits of FIGS. 1, 4, 6, 7, and/or 12 in accordance with thepresent invention.

For simplicity and clarity of the illustration(s), elements in thefigures are not necessarily to scale, some of the elements may beexaggerated for illustrative purposes, and the same reference numbers indifferent figures denote the same elements, unless stated otherwise.Additionally, descriptions and details of well-known steps and elementsmay be omitted for simplicity of the description. As used herein currentcarrying element or current carrying electrode means an element of adevice that carries current through the device such as a source or adrain of an MOS transistor or an emitter or a collector of a bipolartransistor or a cathode or anode of a diode, and a control element orcontrol electrode means an element of the device that controls currentthrough the device such as a gate of an MOS transistor or a base of abipolar transistor. Additionally, one current carrying element may carrycurrent in one direction through a device, such as carry currententering the device, and a second current carrying element may carrycurrent in an opposite direction through the device, such as carrycurrent leaving the device. Although the devices may be explained hereinas certain N-channel or P-channel devices, or certain N-type or P-typedoped regions, a person of ordinary skill in the art will appreciatethat complementary devices are also possible in accordance with thepresent invention. One of ordinary skill in the art understands that theconductivity type refers to the mechanism through which conductionoccurs such as through conduction of holes or electrons, therefore, thatconductivity type does not refer to the doping concentration but thedoping type, such as P-type or N-type. It will be appreciated by thoseskilled in the art that the words during, while, and when as used hereinrelating to circuit operation are not exact terms that mean an actiontakes place instantly upon an initiating action but that there may besome small but reasonable delay(s), such as various propagation delays,between the reaction that is initiated by the initial action.Additionally, the term while means that a certain action occurs at leastwithin some portion of a duration of the initiating action. The use ofthe word approximately or substantially means that a value of an elementhas a parameter that is expected to be close to a stated value orposition. However, as is well known in the art there are always minorvariances that prevent the values or positions from being exactly asstated. It is well established in the art that variances of up to atleast ten percent (10%) (and up to twenty percent (20%) for someelements including semiconductor doping concentrations) are reasonablevariances from the ideal goal of exactly as described. When used inreference to a state of a signal, the term “asserted” means an activestate of the signal and the term “negated” means an inactive state ofthe signal. The actual voltage value or logic state (such as a “1” or a“0”) of the signal depends on whether positive or negative logic isused. Thus, asserted can be either a high voltage or a high logic or alow voltage or low logic depending on whether positive or negative logicis used and negated may be either a low voltage or low state or a highvoltage or high logic depending on whether positive or negative logic isused. Herein, a positive logic convention is used, but those skilled inthe art understand that a negative logic convention could also be used.The terms first, second, third and the like in the claims or/and in theDetailed Description of the Drawings, as used in a portion of a name ofan element are used for distinguishing between similar elements and notnecessarily for describing a sequence, either temporally, spatially, inranking or in any other manner. It is to be understood that the terms soused are interchangeable under appropriate circumstances and that theembodiments described herein are capable of operation in other sequencesthan described or illustrated herein. Reference to “one embodiment” or“an embodiment” means that a particular feature, structure orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, appearancesof the phrases “in one embodiment” or “in an embodiment” in variousplaces throughout this specification are not necessarily all referringto the same embodiment, but in some cases it may. Furthermore, theparticular features, structures or characteristics may be combined inany suitable manner, as would be apparent to one of ordinary skill inthe art, in one or more embodiments.

The embodiments illustrated and described hereinafter suitable may haveembodiments and/or may be practiced in the absence of any element whichis not specifically disclosed herein.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an example of an embodiment of aportion of a drive control circuit 100 that may be configured to controla linear vibration motor (LRA) 102. Circuit 100 may receive a supplyvoltage for operating the elements of circuit 100 between a voltageinput 133 and a voltage return 134. Input 133 may be configured toreceive the operating voltage from a power supply and input 134 may beconfigured to connect to the common reference voltage of the powersupply such as for example a ground reference.

FIG. 2 illustrates in a general manner, a cross-sectional view of anon-limiting example of a linear vibration motor that may be suitablefor use as LRA 102 of FIG. 1. The linear vibration motor (LRA) mayinclude a stator and a vibrator and in some embodiments may include aweight. For example, the magnet may be viewed as the stator and themechanism to which the coil is attached may be considered the vibrator.Drive control circuit 100 may be configured to supply a drive current tothe linear vibration motor (LRA) to cause the weight to oscillate up anddown as illustrated by the arrows. Those skilled in the art willappreciate that other linear vibration motors may also be suitable forLRA 102.

Referring back to FIG. 1, drive control circuit 100 may have anembodiment that may include a drive signal generating circuit or drivecircuit 110, a driver circuit 122, an induced voltage detector circuitor detector circuit 130, and a zero cross detection circuit or zerocross circuit 140. Circuit 122 may have an embodiment of an H-Bridgedriver. Drive signal generating circuit 110 have an embodiment that mayinclude a latch circuit 111, a main counter 112, a loop counter 113, adecoder circuit 114, another latch circuit 115, a difference calculatingcircuit or difference circuit 116, another latch circuit 117, a summingcircuit 118, and another latch circuit 119. Circuits 110-111, 114,116-119, and counters 112-113 may have embodiments that receiveoperating power between input 113 and return 134. An embodiment of drivecircuit 114 may be configured to generate a drive signal 121. In someembodiments, drive signal 121 may be formed to cause LRA 102 to vibrate.In response to signal 121, circuit 122 may be configured to form a drivecurrent 123 that may be delivered to LRA 102. Circuit 100 may beconfigured to form current 123 to include a positive polarity of current123 that flows from output 126 through LRA 102 and into output 127, andmay also include a negative polarity of current 123 that flows intooutput 126 from output 127 through LRA 102. Circuit 100 may beconfigured to generate drive current 123 in response to drive signal 121generated by circuit 110 and then supply the thus generated drivecurrent 123 to LRA 102. Those skilled in the art will appreciate that insome example embodiments, circuit 100 may include circuits 303 and 308and the connections thereto illustrated in FIG. 12 and FIG. 14.

FIG. 3 is a graph having a plot 170 that graphically illustrates in ageneralized manner a non-limiting example embodiment of a waveform ofthe BEMF signal, or alternately a signal that may be representative ofthe BEMF signal, formed at output 127 relative to output 126 for a cycle172 of current 123 that may be formed by an embodiment of circuit 100 inresponse to drive signal 121. For example, the plot 170 may be anon-limiting example of an embodiment of a detect signal 131 fromdetector 130. The abscissa indicates time and the ordinate indicatesincreasing value of the illustrated signal.

Assume for example that plot 170 is a signal that swings fromsubstantially a power supply voltage, such as for example a voltageclose to a Vcc voltage, to a voltage that is substantially a commonreturn voltage, such as for example a ground voltage. Also assume thatthere is a center voltage, such as for example a common mode voltage ora reference voltage, substantially centered to the two voltage levels asillustrated by the centerline of plot 170. Thus, the signal of plot 170and the signal that forms plot 170 swings around that center voltage,such as the level illustrated in a general manner by the centerline inplot 170. Since plot 170 and the signal move around this center voltage(Vc), when plot 170 or the signal thereof crosses that center voltage itis regarded as a zero crossing or a substantially zero crossing of thatsignal or of plot 170. Those skilled in the art will appreciate thatother circuits may form the signal that is representative of the BEMFsignal to have other reference voltages other than the common returnvoltage reference and may form the zero crossings at other voltagelevels. For example, the centerline may be substantially a groundvoltage and the signal may signal may swing above and below that groundvalue such as between a positive supply voltage and a negative supplyvoltage. Thus, plot 170 is a general representation of the BEMF signal.

An embodiment of cycle 172 may occur between two negative-to-positivezero crossings of the BEMF signal, such as for example between zerocrossings 177 and 184. An example of cycle 172 begins as thenegative-to-positive transition of the BEMF signal crosses thecenterline such as for example at a zero crossing 177. As used herein,the term “substantially zero crossing” or the term “zero crossing” meansthat the value of the signal may be plus or minus ten percent (10%) ofthe cycle prior to or after the actual zero crossing of the signal. Theplus or minus ten percent means ten percent of the cycle in time oralternately in radians. Additionally, as used herein, the term“substantially zero crossing” has the same meaning of plus or minus tenpercent regardless of any other definition of the word “substantially”that may be used herein. An upwardly sloped portion or positive slopeportion 176 of the BEMF signal illustrates the value of the BEMF signalrising from a negative value toward a positive value, such as forexample after the end of driving LRA 102 with a negative value ofcurrent 123 and before driving LRA 102 with a positive value of current123. The increasing portion of plot 172 after zero crossing 176illustrates that the BEMF signal has a positive value and is becomingmore positive. A substantially horizontal portion 178 of plot 170 thatis above the center line represents an interval in which circuit 100 maydrive LRA 102 with a positive value of current 123. The portion 178results from current 123 flowing into LRA 102. Portions 173 of plot 170illustrates that in some embodiments the BEMF signal formed by LRA 102may not occur while circuit 100 is driving LRA 102, and the portion 174illustrates that the BEMF signal from LRA 102 may return upon circuit100 terminating driving LRA 102. A downwardly sloped portion or negativesloped portion 179 illustrates the value of the BEMF signal aftertermination of driving LRA 102 with the positive value of current 123and before driving LRA 102 with a negative value of current 123. TheBEMF signal is becoming less positive as portion 179 decreases fromportion 178 to a positive-to-negative zero crossing 180, and the BEMFsignal becomes negative for the portion of plot 170 below zero crossing180. A substantially horizontal portion 182 that is below the centerlineillustrates an interval in which circuit 100 may drive LRA 102 with anegative value of current 123. Portion 182 results from circuit 100driving LRA 102 and in some embodiments the BEMF signal from LRA 102 maynot occur during this portion 182. A positive or upwardly sloped portion183 illustrates the value of the BEMF signal after termination ofdriving LRA 102 with the negative value of current 123 and before againdriving LRA 102 with another positive value of current 123. The BEMFsignal is becoming less negative as portion 183 increases from portion182 to zero crossing 184, and the BEMF signal becomes positive for theportion of plot 170 above zero crossing 184. However, cycle 172 ends atzero crossing 184. A cycle of the BEMF signal resulting from current 123may be defined to start and end at different points of the waveform ofthe BEMF signal in other embodiments. Portion 183 may be similar toportion 176.

The sloped portions 176, 179, and 183 of cycle 172 are formed by thevoltage formed by LRA 102 at output 127 relative to output 126. Becausedrive signal 121 is not active for these sloped portions, circuit 100 isnot driving current to LRA 102, thus, circuit 100 may be configured toform the output of circuit 122, or alternately outputs 126 and 127, tohave a high impedance or HiZ for these sloped portions. In anembodiment, circuit 100 may be configured to drive LRA 102 with current123 for portions 178 and 182 of cycle 172, thus a conducting portion ofa cycle, and to not drive LRA 102 with current 123 for the slopedportions of cycle 172, thus, a non-conducting portion of the cycle andthe outputs may have the HiZ for the non-conducting portions. The timeinterval for the non-conducting portion may be referred to as a HiZinterval. As will be seen further hereinafter, those skilled in the artwill appreciate that an embodiment of counter 112 may be configured tocount time intervals of cycle 172 while circuit 100 is forming drivesignal 121 for cycle 172. In one example embodiment, counter 112 may beconfigured to count from 0 to 199 during cycle 172, thereby formingapproximately 200 time intervals for drive signal 121 during cycle 172.Those skilled in the art will appreciate that an embodiment of circuits112 and 113 may be configured to form cycle 172 for current 123. Circuit100 may also have an embodiment wherein circuits 114-118 and theconnections thereto may be configured to estimate the eigen frequencyand to form the adjusted value for the frequency of signal 121.

Referring back to FIG. 1, detector circuit 130, may have an embodimentthat may be configured to be connected to LRA 102 and detect adifference of electrical potentials at the both ends of the coil of LRA102. Circuit 130 may be configured to be connected to outputs 126 and127 to receive the BEMF signal formed by LRA 102. Circuit 130 may beconfigured to detect the BEMF signal formed between outputs 126 and 127by LRA 102 during the time interval that circuit 100 is not driving LRA102 with current 123, thus, the non-conducting portion of the cycle ofcurrent 123. An embodiment of circuit 130 may be connected to outputs126 and 127 instead of directly to the coil of LRA 102. Circuit 130 mayhave an embodiment that may form detect signal 131 that may berepresentative of the BEMF signal. An embodiment of circuit 140 may beconfigured to detect zero crosses of the BEMF signal detected by circuit130 or alternately to detect zero crossing of signal 131.

An embodiment of circuit 100 or alternately circuit 110 may beconfigured to estimate an eigen frequency for LRA 102 and to control oradjust the drive frequency or frequency of drive signal 121, thus of thefrequency and the time interval or period of a cycle 172, to be as closeto the estimated eigen frequency as possible. Those skilled in the artwill appreciate that the eigen frequency is a natural resonant frequencyof the LRA, and in some embodiments may be the fundamental of thenatural resonant frequency. Circuit 100 may have an embodiment that maybe configured to estimate the eigen function for LRA 102 from a detectedposition of the zero crossing of the back EMF voltage detected bycircuit 140. Circuit 100 may be configured to adaptively vary or controlthe frequency of drive signal 121, thus the frequency of current 123, tobe substantially the same as, or alternately close to, the estimatedeigen frequency of LRA 102. In an embodiment, circuit 100 may beconfigured to adaptively vary or control the frequency of drive signal121 to be no more than one-half of a percent (0.5%) greater than or lessthan the estimated eigen frequency. An embodiment may be configured tovary the frequency of drive signal 121 over a range of plus or minusfifty percent (50%) from a nominal value of the frequency. This functionor method may be referred to as a resonant frequency search method orresonant frequency search mode and a circuit that is configured toperform the method or operate with these functions operates in thismanner may be referred to as a resonant frequency search circuit.Operating in such a manner or method may be referred to as operating ina closed loop run mode.

An embodiment of circuit 110 may also include a register setting circuit135 that may be configured to set an initial or starting value for thefrequency of drive signal 201, thus, set an initial frequency for signal121. For example, in response to circuit 100 being enabled to startforming current 123 to start vibrating LRA 102, circuit 135 may beconfigured to set an initial frequency for signal 121. In an embodiment,circuit 135 may be configured to supply an initial value to circuits 111and 119 as illustrated by the initial value label. Circuit 100 may thenbegin operating in the resonant frequency search mode to form current123, to determine the estimated eigen frequency for LRA 102, and toadjust the frequency of signal 121 to substantially the estimated eigenfrequency. An embodiment of circuit 100 may include that during the HiZinterval of the cycle during the run mode the BEMF signal may beamplified by an amplifier of detector circuit 130 and form signal 131that is representative of the BEMF signal. The amplified signal 131 fromdetector 130 may be received by comparator 141. If the BEMF signal, orthe signal that is representative thereof, crosses the value of thereference signal received by comparator 141, the output of comparator141 changes state. For example, if the BEMF signal is increasing, theoutput of comparator 141 may be asserted in response to the crossing, orif the BEMF signal is decreasing, the output of comparator 141 may benegated in response to the crossing, or alternately vice versa. Detectorcircuit 142 may detect the transitions of the output of comparator 141and form an asserted a detection signal indicating detection of the zerocrossing or substantially zero crossing, and vice versa. Circuit 204 mayuse the detected edges to determine the count of counter 112 anddetermine if the frequency of drive signal 121 needs to increase ordecrease in order to be substantially the same or near to the eigenfrequency of LRA 102. For example, circuit 115 may be configured tolatch the value of counter 112 in response to the asserted state ofcircuit 142. Circuit 116 may be configured to determine the center ofthe latched value and compare that to a center value used for settingcounter 112. The difference may be used to form a new starting value forcounter 112 to change the frequency of signal 121.

Detector 130 may include an embodiment that may be configured toestimate the position of the vibrator portion of LRA 102 by monitoringthe BEMF signal formed by LRA 102 during the non-conducting portion. Asmall value, including a zero value, of the BEMF signal may indicatethat the vibrator is at rest (for example, the vibrator may bepositioned in a maximum reachable point at a south pole side or in amaximum reachable point at a north pole side of LRA 102). Thus, circuit100 may be configured to determine the estimated eigen frequency of LRA102 in such a manner that circuit 140 may be configured to detect thetiming with which the BEMF signal across the coil (such as for examplethe voltage between output 127 relative to output 126) crosses zero andmay also be configured to measure a time interval between the thusdetected zero crosses. The time interval between contiguous zero crossesmay indicate a time interval of a half of a drive cycle of current 123,whereas the time interval between every other zero crossing may indicatea time interval of a full drive cycle of current 123.

Circuit 100 may include an embodiment that may be configured to detectonly the timing with which the BEMF signal across the coil (signalbetween outputs 126 and 127 for example), or alternately signal 131,crosses zero as the BEMF signal is increasing from a negative voltage toa positive voltage during a non-conducting portion of a drive cycle,such as for example for portion 176 or 183 of cycle 172 (FIG. 3). Insuch a case, comparator 141 may be configured to form a negated outputsignal while the BEMF signal is lower than a threshold value, andcomparator 141 may be configured to form an asserted output signal asthe BEMF signal becomes higher than that threshold value or anotherthreshold value. For example, comparator 141 may be configured to form anegated output signal while the output voltage of detector 130 is lowerthan a threshold value, whereas comparator 141 may be configured to forman asserted output signal as the output voltage of detector 130 becomeshigher than a threshold value. The time interval between the assertedand negated values may be used to estimate the eigen frequency of LRA102. For example, detector 130 and circuits 140, 115, and 116 may havean embodiment as a circuit that may be configured to receive the BEMFsignal from LRA 102 and to selectively measure a first frequency of avibration of the linear vibration motor, for example the estimated eigenfrequency. Circuit 110 may be configured to responsively adjust thefrequency or the time interval of the cycle of the next drive signal 121that is used to drive LRA 102. Such operation may be referred to as theclosed loop run mode. Comparator 141 may have an embodiment that isconfigured to operate without hysteresis, or substantially withouthysteresis. Those skilled in the art will understand that there may besome unintentional offset between the inputs to comparator 141 due toprocess tolerances, but these are not considered as forming a hysteresisoperation for comparator 141. Operating substantially without hysteresismay facilitate more accurately detecting the substantially zerocrossing.

Circuit 100 may also include an embodiment that may be configured torepeat the measurement and the adjustment operations for one or morecycles of current 123, such as for example one or more consecutivecycles, so that drive control circuit 100 can continuously drive LRA 102at substantially the estimated eigen frequency or a frequency near tothe estimated eigen frequency of LRA 102. This function or method may bereferred to as the resonant frequency search mode and a circuit that isconfigured to perform the method may be referred to as a resonantfrequency search circuit. Operating in such a manner or method may bereferred to as operating in the closed loop run mode.

In some embodiments, circuit 100 may be configured to operate a brakemode control method and may include associated circuits for controllingand/or performing a brake mode method. This function and relatedcircuits and method may sometimes be referred to as a stop mode ofoperation or a braking mode of operation or a brake mode or a stopcircuit or a brake circuit or braking circuit. For example, in responseto terminating running and driving of LA 102, such as a non-limitingexample of terminating operation in the closed loop run mode oralternately stopping to provide positive and negative pulses of current123 to LRA 102 to drive LRA 102 to vibrate or increase vibration,circuit 110 may be configured to control drive signal 121 to form ananti-drive signal that includes forming current 123 as pulses that havea phase that is opposite to the phase of the drive signal used to driveLRA 102 during the closed loop run mode or during an open loop run mode.Those skilled in the art will appreciate that the anti-drive waveform ofcurrent 123 may have an embodiment that may look substantially like thewaveform of cycle 172 of FIG. 3. Operating in the brake mode may includeforming the anti-drive signal with an anti-drive frequency and mayinclude forming a brake mode of an anti-drive current for current 123 tohave a substantially opposite phase such that the substantially oppositephase may also include conducting portions and also non-conductingportions. Circuit 122 may be configured to form a high impedance state,for example a high output impedance during portions of or substantiallyall of the non-conducting portions of anti-drive signal. For the brakemode, circuit 122 may be configured to form the brake mode of current123 with an anti-drive phase that is substantially opposite to the phaseused during the closed loop run mode (or during an open loop run mode)and to supply such brake mode of current 123 to LRA 102. This quickensthe stopping of LRA 102. In some embodiments circuit 122 may beconfigured to vary the amplitude of current 123 proportionally to theamplitude of the BEMF signal received from LRA 102. As the brake mode ofcurrent 123 is applied to the coil of LRA 102, the stator may achieve abraking function to slow or to stop the motion of the vibrator oralternately to slow the speed of the stator. Circuit 100 may also havean embodiment that may be configured to adjust the frequency of theanti-drive signal to be substantially the eigen frequency of LRA 102.Adjusting the frequency of the anti-drive signal assists in reducing theamount of time needed to substantially stop LRA 102 from vibrating.

An embodiment of circuit 100 may be configured to detect that LRA 102 issubstantially no longer moving. For example, circuit 110 may beconfigured to estimate, from the detected BEMF signal, a vibration forceafter the running of the linear vibration motor LRA has terminated (endof closed loop run mode or alternately open loop run mode) and tocontrol the brake mode anti-drive signal of opposite phase based on theestimated vibration force. For a non-limiting example, if the BEMFsignal lies within a predetermined voltage range, circuit 110 may beconfigured to determine that LRA 102 has come to a stop. In other words,it is regarded that the vibration force has become zero or less than apredetermined threshold value. When the above condition has been met,circuit 110 can be configured to stop the supply of the anti-drivesignal to circuit 122. In some embodiments after the criterion has beenmet, the anti-drive signal for half of one full cycle may still besupplied to driver unit 122 before the supply thereof is stopped. Notethat herein, the drive termination of LRA 102 means a normal drive stop(end of closed loop run mode or alternately an open loop run mode)excluding the reverse drive period required for the braking control(brake mode) and the anti-drive signal.

In some situations, the extent of vibration of a linear vibration motormay become too great and may cause the weight to hit the case of theLRA. It has been found that in some cases when the vibration of themotor becomes too great and the weight hits the case, the resonantfrequency search mode may have caused the frequency of the drive signalto be greater than a designed resonant frequency of the linear vibrationmotor. When such occurs, the frequency of the drive signal may be farfrom the design frequency of the linear vibration motor and it may causean undesirable audible noise. In some cases, the higher frequency of thedrive signal can reduce the effectiveness of the operation in the brakemode.

FIG. 4 schematically illustrates an example of an embodiment of aportion of a drive control circuit 200 that is configured to control LRA102. Circuit 200, in some embodiments, may be an alternate embodiment ofcircuit 100 (FIG. 1). Circuit 200 includes a resonant frequency searchcircuit 204. An embodiment of circuit 204 may be configuredsubstantially the same as at least a portion of the resonant frequencysearch circuit of FIG. 1. For example, circuit 204 may, in someembodiments, include circuits 111, 115, 116, 117, 118, and 119, orcircuits that operate substantially similarly, and these circuits may,in some embodiments, be configured in substantially the same manner asin circuit 100. Circuit 204 may be configured to operate the resonantfrequency search mode in a manner substantially similar to the resonantfrequency search operation described in the description of circuit 100in FIG. 1. Circuit 200 may have an embodiment that may be configured tooperate in the closed loop run mode in a manner substantially similar tocircuit 100. Circuit 200 may also have an embodiment that may include anenable (EN) signal 201. In some embodiments, an asserted state of signal201 may allow operation of circuit 200 and a negated state may stopcircuit 200 from forming drive signals or anti-drive signals. Circuit200 may include inputs 133 and 134 (FIG. 1) and receive operating powerin the same manner as circuit 100. Circuit 200 may include an embodimenthaving an amplifier circuit 220 that may be an alternated embodiment ofcircuit 130 of FIG. 1. Circuit 220 may include an amplifier 221 havingresistors 222-225 configured to form a gain circuit for amplifier 221.Amplifier 221 may receive a reference signal or a reference voltage(VREF) 228. In an embodiment, reference voltage 228 may form a voltageor signal at the non-inverting input of amplifier 221 that may besubstantially the voltage Vc of FIG. 3. Reference voltage 228 may have avalue that is referenced to the common return voltage of input 134.

An embodiment of circuit 200 may be configured to have three operatingmodes, the closed loop run mode, an open loop run mode, and a brakemode. Those skilled in the art will appreciate that in some exampleembodiments, circuit 200 may include circuits 303 and 308 and theconnections thereto illustrated in FIG. 12 and FIG. 14.

FIG. 5 is a graph having plots that illustrate example embodiments ofsome signals that may be formed by circuit 200 during operation in theclosed loop run mode, the open loop run mode, and the brake mode. Theabscissa indicates time and the ordinate indicates increasing value ofthe illustrate signal. A plot 213 illustrates a non-limiting exampleembodiment of the BEMF signal formed at output 127 relative to output126. Portions 214 illustrate in a general manner a non-limiting exampleof the BEMF signal during the non-conducting portions of current 123.Those skilled in the art will appreciate that the signal may have othervalues for the conducting portion of the cycle as illustrated in generalmanner by other portions of plot 213. Additionally, all of thenon-conducting portions of plot 213 are not labeled for clarity of thedrawings. Those skilled in the art will appreciate that plot 213 hassubstantially the same elements as plot 170 (FIG. 3) but illustratesmore than one cycle of the BEMF signal. A plot 216 is not a signalformed or received by circuit 200 but is an illustration of theintensity of the vibration motion of LRA 102. A plot 217 illustrates oneexample embodiment of current 123 A plot 218 illustrates a non-limitingexample of some possible values of counter 112, and a plot 219illustrates a non-limiting example of some possible conditions of signal211. This description has references to FIGS. 4 and 5.

In an embodiment, circuit 200 may be configured to operate in the samemanner as circuit 100 operates in the closed loop run mode. Thus, in theclosed loop run mode, an embodiment of circuit 200 may be configured toform drive signal 121 at a first frequency and form current 123 at thefirst frequency. Circuit 200 may also be configured to estimate theeigen frequency of LRA 102 and to adjust the first frequency to afrequency that is substantially the estimated eigen frequency or afrequency near to the estimated eigen frequency of LRA 102 in responseto detecting the estimated eigen frequency of LRA 102. Circuit 200 mayinclude an embodiment that operates in the closed loop run mode for afirst number of cycles of drive signal 121, wherein forming drive signal121 includes adjusting the first frequency to a second frequency that isnear to the eigen frequency in response to detecting the eigen frequencyof LRA 102. One non-limiting example of this type of operation isillustrated in FIG. 5 during the operation labeled closed loop. Forexample, an embodiment of circuit 200 may include that during the HiZinterval of the cycle during the run mode the BEMF signal may beamplified by amplifier 221 and form a signal 226 that is representativeof the BEMF signal. In some embodiments, signal 226 may be substantiallysimilar to or alternately the same as, signal 131 (FIG. 1).

Circuit 200 may also include an embodiment that operates in an open looprun mode to drive LRA 102 to vibrate after forming the first number ofdrive cycles of drive signal 121 and current 123 in the close loop runmode. In the open loop run mode, circuit 200 may be configured to formdrive signal 121, and current 123, at a third frequency. The thirdfrequency may be substantially the frequency used for the last cycle ofdrive signal 121 during the closed loop run mode. In another embodiment,circuit 200 may be configured to form the third frequency at a frequencythat is different from the second frequency that was used for the lastcycle in the closed loop run mode. For example, circuit 200 may beconfigured to form the third frequency to be substantially the firstfrequency or some other frequency in other embodiments. Circuit 200 maybe configured to operate at the third frequency for a second number ofcycles of drive signal 121 or of current 123. In the open loop run mode,an embodiment of circuit 200 may be configured to not adjust the thirdfrequency and to disable operation of the resonant frequency searchmode. In an embodiment, circuit 200 may be configured to maintain thethird frequency substantially constant during operation in the open looprun mode. Circuit 200 may be configured to maintain the third frequencysubstantially constant for the duration of the open loop run mode. Inanother embodiment, circuit 200 may be configured to change thefrequency of signal 121 and current 123 during the open loop run mode toanother frequency but not to the estimated eigen frequency.

Circuit 200 may further include an embodiment wherein circuit 210 may beconfigured to control enabling and disabling circuit 200 from operationwith the resonant frequency search mode. For example, circuit 210 may beconfigured to enable and disable circuit 200 from adjusting thefrequency of drive signal 121 in response to detecting and determiningthe eigen frequency of LRA 102. Circuit 210 may have an embodiment thatmay be configured to inhibit one of or both of detecting or determiningthe estimated eigen frequency. An embodiment of circuit 210 may beconfigured to monitor a value of loop counter 113 to determine thenumber of cycles of drive signal 121 or current 123 that are formed.After forming the first number of cycles in the closed loop run mode,circuit 210 may be configured to assert an ON/OFF control signal 211 tocause circuit 200 to start operation in the open loop run mode. Inresponse to the asserted value of ON/OFF control signal 211, circuit 200may be configured to form drive signal 121 and current 123 at the thirdfrequency and to terminate adjusting the value of drive signal 121. Forexample, the ON/OFF signal may be used to inhibit circuit 204 fromreceiving the output of circuit 142 or to selectively force the input tocircuit 204 to a value which inhibits the estimation operation. Circuit200 may include an embodiment in which circuit 210 monitors the value ofloop counter 113 to determine the number of cycles of drive signal 121that are formed in the open loop run mode, and to negate the ON/OFFsignal in response to completing the second number of cycles of drivesignal 121 in the open loop run mode, such as illustrated in FIG. 5 atthe end of the operation labeled “open loop”. In response to completingthe second number of cycles of drive signal 121, circuit 200 may beconfigured to begin operating in the brake mode and forming theanti-drive signal 121 to form the negative phase current signal. Anembodiment may include that circuit 200 may be configured to re-enablethe resonant frequency search mode and to begin adjusting the anti-drivefrequency of drive signal 121 and current 123 to substantially theestimated eigen frequency while operating in the brake mode.

An embodiment may include that circuit 200 may be configured to operatein the brake mode after completing the last cycle of drive signal 121,and/or current 123, in the open loop run mode. Circuit 200 may beconfigured to, when operating in the brake mode, form drive signal 121,and resulting drive current 123, at an anti-drive frequency. Theanti-drive signal may have a cycle substantially the same as cycle 172illustrated in FIG. 3. The anti-drive frequency may be the thirdfrequency and to, when operating in the brake mode, adjust theanti-drive frequency or alternately the third frequency in response todetecting and determining the estimated eigen frequency of LRA 102. Inother embodiments, circuit 200 may be configured to form drive signal121 at a different frequency in response to operating in the brake mode.For example, circuit 200 may begin operating in the brake mode andforming drive signal 121 at the first frequency and to then adjust thefirst frequency in response to detecting and determining the estimatedeigen frequency of LRA 102. Alternately, circuit 200 may be configuredto begin operating in the brake mode and forming drive signal 121 at thesecond frequency or some other frequency, in response to operating inthe brake mode, as long as circuit 200 is configured to adjust the otherfrequency in response to detecting and determining the estimated eigenfrequency of LRA 102. In some embodiments, circuit 200 may be configuredto adjust the anti-drive frequency of signal 121 for each cycle ofsignal 121. Circuit 200 may have a non-limiting example embodimentwherein the operation in the brake mode is substantially the same as thebrake mode operation of circuit 100 except that circuit 200 may beconfigured to use the third frequency to begin operating in the brakemode. An embodiment of circuit 200 may be configured to detect that LRA102 is substantially no longer moving. For example, circuit 204 may beconfigured to estimate, from the detected BEMF signal, a vibration forceafter the running of the linear vibration motor LRA has terminated (endof closed loop run mode or alternately open loop run mode) and toterminate forming the brake mode anti-drive signal based on theestimated vibration force. In another embodiment, circuit 200 may beconfigured to operate in the brake mode for a desired number of cycles.In an embodiment, counter 113 may be configured to count the number ofcycles in the brake mode and assert a signal that is used by circuit 200to terminate forming anti-drive cycles. Adjusting the frequency of thedrive signal when operating in the brake mode assists in reducing theamount of time required to stop the vibration of LRA 102.

By disabling the resonance frequency search operation, or operating inthe open loop run mode, there is no need to analyze the back EMF voltagefrom the LRA with an analog-to-digital converter and no need to have afunction to adjust the driving voltage with a feedback of vibrationforce. Thus, the size of circuit 200 can be reduced which can reduce thesystem cost. Additionally, even if the drive signal causes the weight ofthe LRA to hit the case, the frequency of the drive signal is stillsubstantially the eigen frequency or very near thereto thus, the brakemode can begin with a drive frequency that is near to the eigenfrequency. Forming brake mode to use substantially the estimated eigenfrequency improves the feel of the system that uses circuit 200.

FIG. 6 schematically illustrates an example of an embodiment of acircuit that may be an alternate embodiment of circuit 114 that isillustrated in FIGS. 1 and 4. Circuit 114 includes a brake controlcircuit or stop control circuit 61 that may be configured to form thehigh impedance state and insert the high impedance period and also maybe configured to assist in forming the anti-drive signals of the brakemode.

Some embodiments described herein may be related to either or both ofU.S. Pat. No. 8,736,201, issued to Tsutomu Murata on May 27, 2014 andU.S. Pat. No. 8,829,843, issued to Tsutomu Murata on Sep. 9, 201, bothof which are hereby incorporated herein by reference.

From all the foregoing, one skilled in the art will appreciate that anembodiment of a semiconductor device may include a circuit forcontrolling a linear vibration motor that may comprise:

a first circuit, such as for example circuit 110, configured to form adrive signal (121) to control a frequency of a drive current, such asfor example current 123, through the linear vibration motor;

a second circuit, such as for example circuit 204, configured toselectively measure a first frequency of a vibration of the linearvibration motor;

the circuit, such as for example either of circuits 100 or 200,configured to operate in a closed loop run mode and form the drivecurrent at a first frequency and to adjust the first frequency to asecond frequency that is substantially the frequency of the vibration ofthe linear vibration motor in response to a difference between the firstfrequency and the frequency of the vibration of the linear vibrationmotor;

the circuit configured to operate in the closed loop run mode for afirst number of cycles of one of the drive current or the drive signal;

the circuit configured to operate in an open loop run mode for a secondnumber of cycles of one of the drive current or the drive signal inresponse to an end of the first number of cycles, the circuit configuredto form the drive current at a substantially fixed frequency for thesecond number of cycles, the drive current having a first phase; and

the circuit configured to operate in a brake mode and to form the drivecurrent with a second phase that is opposite to the first phase inresponse to expiration of the second number of cycles, the circuitconfigured to selectively measure a second frequency of a vibration ofthe linear vibration motor while operating in the brake mode, to formthe drive current with a third frequency and to adjust the thirdfrequency to be substantially the second frequency of the vibration ofthe linear vibration motor.

An embodiment may include that the circuit may be configured toselectively disable the second circuit and to not measure the frequencyof the vibration of the linear vibration motor in response to the end ofthe first number of cycles of the drive current.

In another embodiment, the circuit may be configured to selectivelyenable the second circuit and to measure the frequency of the vibrationof the linear vibration motor in response to the end of the secondnumber of cycles.

The circuit may have an embodiment that may include a counter configuredto count cycles of the drive signal, wherein the circuit is configuredto selectively enable operation in the open loop run mode in response tothe counter counting the first number of cycles.

An embodiment may include that the circuit may be configured toselectively enable operation in the brake mode in response to thecounter counting the second number of cycles. Another embodiment mayinclude that the circuit may be configured to selectively terminateoperation in the brake mode in response to the counter counting a thirdnumber of cycles.

Those skilled in the art will appreciate that a circuit for controllinga linear vibration motor may comprise:

a first circuit, such as for example a circuit 110, configured to form adrive signal to control a frequency of a drive current through thelinear vibration motor to cause a vibration of the linear vibrationmotor, the drive current having a first phase;

a second circuit, such as for example circuit 204 or portions of circuit110, configured to selectively measure a frequency of a vibration of thelinear vibration motor; and

the circuit configured to form the drive current with a first frequencyand a second phase that is opposite to the first phase to slow thevibration of the linear vibration motor, the circuit configured toselectively enable the second circuit to measure the frequency of thevibration of the linear vibration motor and to adjust the firstfrequency to a third frequency that is substantially the frequency ofthe vibration of the linear vibration motor in response to a differencebetween the first frequency and the frequency of the vibration of thelinear vibration motor.

An embodiment of the circuit may be configured to determine an intensityof the vibration of the linear vibration motor and to terminate formingthe drive current in response to the intensity of the vibration beingless than a vibration threshold value.

In an embodiment, the circuit may be configured to not adjust the firstfrequency during other portions of the drive current.

An embodiment of the second circuit may include a resonant frequencysearch circuit configured to estimate a frequency of a back EMF signalreceived from the linear vibration motor.

In an embodiment, the resonant frequency search circuit may beconfigured to measure a time between to two negative to positive zerocrossing transitions of the back EMF signal and estimate an eigenfrequency of the linear vibration motor.

The circuit may have an embodiment that may include a detector circuitconfigured to receive the back EMF signal from the linear vibrationmotor, and includes a zero crossing circuit configured to detect zerocrossings of the back EMF signal.

An example of an embodiment of a semiconductor device may comprise:

a control circuit of the semiconductor device configured to form a drivesignal to form a drive current at a drive frequency to and a first phaseto a linear vibration motor during one of an open loop run mode or aclosed loop run mode;

a first circuit of the control circuit configured to form an anti-drivesignal having an anti-drive frequency and a second phase that issubstantially opposite to the first phase wherein the anti-drive signalhas non-conducting portions of a cycle of the anti-drive signal; and

the control circuit configured to form an estimated eigen frequency ofthe linear vibration motor in response to a non-conducting portion ofthe anti-drive signal having a first slope and to adjust the anti-drivefrequency to another frequency that is substantially the estimated eigenfrequency, wherein the control circuit is configured to determine if avibration of the linear vibration motor is less than a thresholdvibration value in response to a non-conducting portion having a secondslope that is opposite to the first slope and to terminate forming theanti-drive signal.

Those skilled in the art will appreciate that a method of forming asemiconductor device may comprise:

configuring a circuit of the semiconductor device to form a drive signalto form a drive current to apply to a linear vibration motor;

configuring the circuit to form an estimate of an eigen frequency of thelinear vibration motor;

configuring the circuit to form the drive signal at a drive frequencyand a first phase and configuring the circuit to adjust the drivefrequency to a first frequency that is substantially the estimate of theeigen frequency of the linear vibration motor; and

configuring the circuit to form an anti-drive signal at an anti-drivefrequency and a second phase that is substantially opposite to the firstphase, and configuring the circuit to adjust the anti-drive frequency ofthe anti-drive signal to another frequency that is substantially theestimate of the eigen frequency of the linear vibration motor.

An embodiment of the method may include configuring the circuit estimatethe eigen frequency for each cycle of the anti-drive signal and toadjust the anti-drive frequency for each cycle of the anti-drive signal.

In another embodiment the method may include configuring the circuit toselectively enable adjusting the drive frequency to substantially theestimate of the eigen frequency for a first number of cycles of thedrive signal and to form the drive frequency at a substantially constantfrequency for a second number of cycles of the drive signal wherein thesecond number of cycle is subsequent to the first number of drivecycles.

An embodiment may include configuring a counter to count cycles of drivesignal to determine the first and second number of drive cycles.

Another embodiment may include configuring the circuit to selectiveenable the circuit to estimate the eigen frequency in response toforming the anti-drive signal.

In an embodiment, the method may include configuring the circuit tomeasure a time between multiple zero crossings of a back EMF signalreceived from the linear vibration motor.

The method may have an embodiment may include configuring the circuit toreceive a back EMF signal from the linear vibration motor.

An embodiment may include configuring the circuit to measure the timebetween multiple zero crossings of the back EMF signal and use the timebetween multiple zero to estimate the eigen frequency of the linearvibration motor.

FIG. 7 schematically illustrates an example of an embodiment of aportion of a control circuit 230 that is configured to control LRA 102.Circuit 230, in some embodiments, may be an alternate embodiment ofcircuit 100 (FIG. 1) or alternately of circuit 200 of FIG. 4. Circuit230 may include a resonant frequency search circuit 239. An embodimentof circuit 239 may be configured substantially the same as and operatesubstantially the same as at least a portion of the resonant frequencysearch circuit of FIG. 1 or substantially the same as at least a portionof resonant frequency search circuit 204 of circuit 200 (FIG. 4). Forexample, circuit 239 may, in some embodiments, include circuits 111,115, 116, 117, 118, and 119 configured in the substantially the samemanner as configured for circuit 100 (FIG. 1) and may be configured tooperate in a manner substantially similar to or substantially the sameas the operation of the resonant frequency search mode described in thedescription of FIG. 1 or alternately substantially the same as at leasta portion of the resonant frequency search mode formed by circuit 200 ofFIG. 4. Circuit 239 may also include an embodiment that may beselectively enabled to operate circuit 230 in the resonant frequencysearch mode and to selectively disable operation in the resonantfrequency search mode. Circuit 230 may have an embodiment that mayinclude a stop detect circuit 235, a counter latch circuit 237, and amode selector circuit 240. In some embodiments, circuit 237 may besubstantially similar to and operate substantially the same as circuit115 of FIG. 1. Circuit 240 may have an embodiment that may besubstantially similar to and operate substantially the same as circuit210 of FIG. 4 except that circuit 240 is also configured to control thebrake mode as will be seen further hereinafter.

An embodiment of circuit 230 may also include a hysteresis comparator241. Comparator 241 may be similar to a comparator 41 and the relatedhysteresis circuitry, such as in FIGS. 11 and 16, as explained in U.S.Pat. No. 8,736,201, issued to Tsutomu Murata on May 27, 2014 which ishereby incorporated herein by reference. As will be seen furtherhereinafter, an embodiment of comparator 241 may be configured toselectively operate as a hysteresis comparator or to selectively operateas a non-hysteresis comparator. Those skilled in the art will appreciatethat in some example embodiments, circuit 230 may include circuits 303and 308 and the connections thereto illustrated in FIG. 12 and FIG. 14.

In some systems that use an LRA, the LRA may be used to provide tactilefeedback to a person that is touching the system, such as for example atouch screen of a smartphone or a tablet. For control systems that use abraking function or brake mode for controlling the LRA, it sometimes mayhappen that the brake signals are out of phase with vibration of theLRA, such as for example not in phase with the vibration of the movingparts of the LRA, such as for example the yoke and the weight.

Further, in some applications, a controller may set a HiZ intervalduring an active time of the drive signal, such as for example withinthe portion of the drive cycle time interval that the drive signal is toform the non-conducting portion of the cycle, and may check thevibration force of the motor by monitoring the BEMF signal during theHiZ period. If the BEMF signal received during the HiZ period is lessthan a threshold value, then it may be determined that the LRA hassubstantially ceased vibrating and the anti-drive signal during thebrake mode may be terminated.

Referring back to FIG. 7, circuit 230 may include an embodiment that maybe configured similarly to circuit 200 to have three operating modes, aclosed loop run mode, an open loop run mode, and a brake mode asdescribed for circuit 200. Another embodiment of circuit 230 may beconfigured to include a closed loop run mode and a brake mode asdescribed for circuit 100. Thus, circuit 230 may be configured tooperate in the brake mode by forming the anti-drive signal. In someembodiments, the brake mode may include adjusting the frequency of theanti-drive signal to be substantially the same as or near to theestimated eigen frequency of LRA 102.

Circuit 230 may also include an embodiment that may include a sync-brakemode that in some embodiments may be different than the brake mode ofeither of circuits 100 or 200; however, the sync-brake mode of operationand any of the related circuits of circuit 230 may be used as a portionof either of circuits 100 or 200. An embodiment of circuit 230 may beconfigured to form a drive signal 201 that may include all of theembodiments of signal 121 explained in the descriptions of FIGS. 1-6,and additionally, signal 201 may also include signals for the sync-brakemode of operation.

FIG. 8 illustrates in a general manner a flow chart 250 that illustratesin a general manner an embodiment of some steps in an embodiment of amethod of operation for the sync-brake mode formed by one or moreembodiments of circuit 230.

FIG. 9 is a graph having three plots that illustrate some non-limitingexamples of some signals that may be formed during the operation of anembodiment of circuit 230. Plots 265-267 graphically illustrate in ageneralized manner some non-limiting example embodiments of differentwaveforms for the BEMF signal for a cycle 172 of current 123 that may beformed by a circuit 230 in response to drive signal 201. The individualelements of plots 265-267 represent the same portions of a waveform ofthe BEMF signal as explained in the description of plot 170 of FIG. 3,such as for example the conducting and non-conducting portions. Plots268-270 illustrate in a general manner examples of possible states ofthe output of comparator 241 for the cycle illustrated by respectiveplots 265-267. The abscissa indicates time and the ordinate indicatesincreasing value of the illustrate signals. This description hasreferences to FIGS. 7-9.

Assume for an example, that an embodiment of main counter 112 may beconfigured to count from 0-199 time intervals during a cycle of drivesignal 201 or alternately of drive signal 121. The numbers 0-199 onplots 265-267 represent a non-limiting example of possible values formain counter 112 and possible time intervals during cycle 172 of drivesignal 201.

Steps 251 and 252 of flowchart 250 illustrate a portion of a method inwhich an embodiment of circuit 230 operates in the run mode and does notoperate in the sync-brake mode, thus, circuit 230 may be configured tooperate to form drive signal 201 with a drive frequency to drive LRA 102and cause LRA 102 to vibrate. For example, circuit 230 may be operatingin either the closed loop run mode or open loop run mode.

Assume for example, that circuit 230 completes operation in the run mode(closed loop or open loop) and transitions to the sync-brake mode asillustrated at a step 253. An embodiment of circuit 230 may beconfigured to form the anti-drive signal for drive signal 201 with ananti-drive frequency and form current 123 having a phase that isopposite to the phase used to form current 123 during the run mode(either open or closed loop). As explained hereinbefore, an embodimentof the sloped portions of the waveform of current 123 represents apositive slope or a negative slope of the BEMF signal and the outputs ofcircuit 230 may have the HiZ state for these non-conducting portions ofthe cycle. An embodiment of circuit 230 may be configured to monitor theBEMF signal received between outputs 126 and 127 during at least aportion of the HiZ time intervals. During at least a portion of the HiZtime interval of one of either the positive slope or the negative slope,circuit 230 may be configured to operate using the resonant frequencysearch mode and adjust the anti-drive frequency of the anti-drive signalto substantially the estimated value of the eigen frequency of LRA 102.For example, determine the eigen frequency of LRA 102 and adjust thefrequency of the anti-drive signal. During at least a portion of thetime interval of an opposite one of either the positive slope or thenegative slope, circuit 230 may be configured to determine if theintensity of the vibration of LRA 102 is less than a vibration thresholdvalue then terminate the sync-brake mode in response thereto, such asfor example as illustrated in steps 257-260. For example, terminateforming the anti-drive signal to slow the vibration action of LRA 102.If the vibration force is greater than the vibration threshold value,circuit 230 may be configured to continue operating in the sync-brakemode as illustrated at steps 259 and 253.

Steps 253-256 of flowchart 250 illustrate a method of forming andcontrolling the anti-drive signal wherein the positive or rising slopeof the waveform of current 123 may be used to determine the eigenfrequency and operate using the resonant frequency search mode andadjust the frequency of the anti-drive signal. For example, circuit 230may be configured to use the substantially zero crossings of thepositive slope of the BEMF signal to determine the eigen frequency ofLRA 102. An embodiment of circuit 230 may be configured to use thesubstantially zero crossings of only the positive slope of the BEMFsignal to determine the eigen frequency of LRA 102. In response tooperation using the resonant frequency search mode in the sync-brakemode, circuit 230 may be configured to selectively disable comparator241 from operating with hysteresis and selectively enable comparator 241to operate as a regular comparator as illustrated at step 255. Using thenon-hysteresis mode when operating in the frequency search modefacilitates more accurately detecting the zero crossing or substantiallyzero crossing. For example, comparator 241 may be configured to detectthe substantially zero crossings and circuit 237 may form a signalrepresenting the edges of the output of comparator 241 that correspondto the substantially zero crossings of the positive slope of the BEMFsignal. Circuit 230 may be configured to use these zero crossings of thepositive slope of the BEMF signal to determine the eigen frequency andadjust the frequency of signal 201.

Steps 257-260 illustrate an example of a method of forming andcontrolling the anti-drive signal wherein the negative slope of the BEMFsignal is used to measure and to detect the intensity of the vibrationof LRA 102. Circuit 230 may have an embodiment that uses only thenegative slope of the BEMF signal, or alternately the time intervalthereof, to measure and to detect the intensity of the vibration of LRA102. If the vibration has decrease to less than the vibration thresholdlevel, circuit 230 may be configured to terminate forming the anti-drivesignal to slow the vibration action of LRA 102. In response to operatingto monitor the BEMF signal and determine the intensity of the vibrationof LRA 102 in the sync-brake mode, circuit 230 may be configured toselectively enable comparator 241 to operate as the hysteresiscomparator as illustrated at step 257. In one embodiment circuit 230 maybe configured to detect that the intensity of the vibration hasdecreased to no greater than the vibration threshold value andresponsively stop forming the anti-drive signal.

An embodiment of circuit 230 may include that during the HiZ intervalthe BEMF signal during the sync-brake mode is amplified by amplifier221. As illustrated at step 257, circuit 230 may be configured toselectively operate comparator 241 in the hysteresis mode to detect thevalue of the output of amplifier 221 being greater than a referencevoltage value plus a hysteresis value. As the vibrations of LRA 102become weaker, the angle or slope of the non-conducing portion of theBEMF signal becomes smaller, thus, the count value of counter 112 willbecome larger as the vibration decreases. Thus, the value of counter 112may be used to detect that the vibration has become less than thevibration threshold value. Step 258 illustrates that an embodiment ofcircuit 230 may be configured to capture the count or value of counter112 in response to comparator 241 detecting the substantially zerocrossing of the BEMF signal during the sync-brake mode. However, thoseskilled in the art will appreciate that in the hysteresis mode, circuit230 may detect a modified zero crossing at a point other than the actualzero crossing because of the hysteresis operation of comparator 241. Forexample, the value of counter 112 may be captured or stored, such as forexample in circuit 115, in response to the output of comparator 241changing state or in an alternate embodiment changing from an assertedto a negated state. If the count value is no less than a threshold countvalue, circuit 230 may be configured to determine that the vibration ofLRA 102 is less than the vibration threshold value and may be consideredto have substantially stopped vibrating. For example, the value or countof main counter 112 may be less than a vibration threshold count todetermine that the vibration intensity is less than the vibrationthreshold value. In an embodiment, if the vibration value is less thanthe vibration threshold value, it is detected that the vibration of LRA102 is less than the vibration threshold value and the sync-brake modemay be terminated, such as for example the anti-drive signal to slow thevibration of LRA 102 may be terminated. In some embodiments, theanti-drive and the drive signals are both terminated. However, if thevalue of the counter indicates that the vibration is greater than thevibration threshold value, the sync-brake mode may still be continued asillustrated by step 259 returning to step 253 in flowchart 250.

The plots of FIG. 9 illustrate three different values of counter 112that may occur for three different intensities of the vibration of LRA102. Assume that an example of the count threshold value may be a countvalue of 120. Plots 265 and 268 illustrate that at one substantiallyzero crossing or the modified zero crossing of the negative slope of theBEMF signal, counter 112 may have a value of 110, thus, circuit 230detects that the vibration intensity is large and returns to step 253 ofchart 250. Plots 266 and 269 illustrate that at one substantially zerocrossing or modified zero crossing of the negative slope of the BEMFsignal, counter 110 may have a value of 118, thus, circuit 230 detectsthat the vibration intensity is still too large and returns to step 253of chart 250. Plots 267 and 270 illustrate that at one substantiallyzero crossing or modified zero crossing of the negative slope of theBEMF signal, counter 110 may have a value of 122. Since the countthreshold value is 120, circuit 230 detects that the vibration intensityis small and operation moves to step 260. Those skilled in the art willappreciate that because of the hysteresis operation of comparator 221and the different slope of the non-conducting portion of the cycle,circuit 230 may assert the signal indicating the detection of the zerocrossing at different places relative to the actual zero crossing.Because of the hysteresis, a less steep slope will result in assertingthe detection signal later in the cycle, for example a modified zerocrossing, than it will for a steeper slope of the BEMF signal, forexample another modified zero crossing. For example, plot 265 has alarge intensity of vibration, so the slope is steeper and the crossingpoint of dashed line and BEMF voltage is near zero crossing point. Onthe other hand, plot 267 has a small intensity, so the slope of BEMF isless and the crossing point of dashed line and BEMF voltage is far fromzero crossing point, for example at a modified zero crossing. There is arelation between intensity of vibration and slope of BEMF and thehysteresis comparator detects a steeper slope quicker than a less steepslope resulting in one example of a modified zero crossing

Thus, circuit 230 may be configured to operate in the sync-brake mode touse the resonant frequency search mode and adjust the frequency of theanti-drive signal to substantially the estimated value of the eigenfrequency of LRA 102 for at least a portion of the HiZ time interval ofonly one of either the positive slope or the negative slope of the BEMFsignal. During at least a portion of the time interval of only anopposite one of either the positive slope or the negative slope, circuit230 may be configured to determine if the intensity of the vibration ofLRA 102 is less than the vibration threshold value then terminate thesync-brake mode.

FIG. 10 is a graph having plots that illustrate another example of amethod for determining if the vibration of the LRA is less than thevibration threshold value and/or a method of adjusting the frequency ofthe anti-drive signal in response to the vibration frequency of the LRA.A plot 290 illustrates the waveform of the signal received at output 127relative to output 126. The portions of the waveform identified in ageneral manner as portions 291 are the BEMF signal formed by LRA 102such as for example the BEMF during the non-conducting portions of thecycle. Portions 292 illustrates in a general manner a portion of divesignal applied to output 127 relative to the common return voltage, suchas for example a ground voltage, during the conduction portions of thecycle. Portions 292 may in some embodiments correspond to portion 178 ofFIG. 3. Portions 293 illustrates in a general manner a portion of thedive signal applied to output 126 relative to the common return voltageduring the conduction portions of the cycle. Portions 293 may in someembodiments correspond to portion 182 of FIG. 3. A plot 274 illustratesan example of the output of comparator 241. A plot 275 illustrates anexample of the intensity of the vibration of LRA 102. As seen in plot275, the vibration intensity decreases in response to the anti-drivesignal having a frequency that is adjusted to be substantially the sameas the vibration frequency of the LRA. An embodiment may include thatthe adjustment may be performed for substantially each cycle of theanti-drive signal of drive signal 201. Using one of the positive or thenegative slope of the BEMF signal to estimate the eigen frequency andadjust the frequency of the anti-drive signal and using the other slopeof the BEMF signal to determine if the vibration has decreased to lessthan the vibration threshold value facilitates using one cycle of theanti-drive signal to quickly reduce the vibration of the LRA as well asdetecting that the vibration has substantially stopped.

FIG. 11 is a graph having plots that illustrate another embodiment ofthe method for adjusting a value of the anti-drive signal of drivesignal 201 including using a value of main counter 112 in response tothe output of comparator 241 changing state, and also operating as anon-hysteresis comparator for the method of adjusting the frequency ofthe anti-drive signal. A plot 276 illustrates an example of some of thecount values for an embodiment of counter 112. A plot 277 illustrates anexample of an embodiment of the output of an embodiment of comparator241 when operating in the non-hysteresis mode, and a plot 278illustrates an example of an embodiment of counter 110 being set with anew count value to adjust the frequency of the anti-drive signal. Assumefor example that at a time T0, the output of comparator 241 changesstate, and that counter 112 has counted to a count to 204. The countvalue of 204 is captured or stored substantially at time T0 and the newstarting value of counter 110 is adjusted to begin counting at four (4)instead of at zero (0) to adjust for the difference between the actualvalue (204) of counter 110 at the end of the previous cycle and thevalue (199) that it should have at the end of that previous cycle.

Configuring circuit 230 to adjust the frequency in one portion of thenon-driven portion of the drive current and to determine if thevibration of the LRA has decreased to less than the vibration thresholdvalue in another portion of a different non-driven phase of the drivesignal may facilitate providing a more usable vibration feedback to theuser of the device incorporating circuit 230.

From all the foregoing, one skilled in the art will understand that asemiconductor device including a control circuit for controlling alinear vibration motor may comprise:

a first circuit, such as for example circuit 110/114, or 122, may beconfigured to form a drive signal, such as for example signal 121, tocontrol a frequency of a drive current, such as for example current 123,through the linear vibration motor;

a second circuit, such as for example circuit 239 or 221 or 224, may beconfigured to receive a back EMF (BEMF) signal from the linear vibrationmotor and to selectively measure a first frequency of a vibration of thelinear vibration motor;

an embodiment of the second circuit may have an output coupled to thefirst circuit to provide a frequency signal to the first circuit;

the control circuit, such as for example circuit 100 or 200 or 230, maybe configured to operate in a closed loop run mode and form the drivecurrent at a drive frequency to cause the linear vibration motor tovibrate, the control circuit configured to adjust the drive frequency tosubstantially the first frequency in response to a difference betweenthe drive frequency and the first frequency;

An embodiment of the control circuit may include a counter to count thenumber of cycles;

the control circuit may be configured to operate in the closed loop runmode for a first number of cycles of one of the drive current or thedrive signal;

the control circuit may be configured to operate in an open loop runmode for a second number of cycles of one of the drive current or thedrive signal in response to an end of the first number of cycles, thecontrol circuit configured to form the drive current at a substantiallyfixed frequency for the second number of cycles, the drive currenthaving a first phase; and

the control circuit the control circuit, such as for example circuit 240together with circuit 114, may be configured to operate in a sync-brakemode and to form the drive current with a second phase that is oppositeto the first phase in response to expiration of the second number ofcycles, the control circuit configured to selectively measure a secondfrequency of a vibration of the linear vibration motor during one of apositive slope or a negative slope of the BEMF signal, the controlcircuit configured to form the drive current with a third frequency andto adjust the third frequency to be substantially the second frequency,and the control circuit configured to selectively measure an intensityof a vibration of the linear vibration motor during a different one ofthe positive slope or the negative slope of the BEMF signal andterminate forming the drive current in response to the vibrationdecreasing to a threshold value.

An embodiment of the control circuit may include a search circuit, suchas for example circuit 239, to estimate the eigen frequency of thelinear vibration motor.

In another embodiment the control circuit may be configured toselectively disable the second circuit and to not measure the frequencyof the vibration of the linear vibration motor in response to the end ofthe first number of cycles of the drive current.

An embodiment may include a comparator that may be configured to receivea first signal that is representative of the BEMF signal and compare thefirst signal to a reference signal, and wherein the control circuit isconfigured to selectively enable the comparator to operate as anon-hysteresis comparator in response to operating to selectivelymeasure the second frequency of the vibration of the linear vibrationmotor.

In an embodiment, the second circuit may be configured to selectivelyenable the comparator to operate as a hysteresis comparator in responseto operating to selectively measure the intensity of the vibration ofthe linear vibration motor.

An embodiment of the control circuit may include that the second circuitmay include an amplifier configured to receive the BEMF signal and formthe first signal that is representative of the BEMF signal.

Another embodiment may include that the control circuit may include acounter configured to count time intervals during a cycle of the drivesignal, the control circuit configured to determine if a count of thecounter is greater than a count threshold value in response to thedifferent one of the positive slope or the negative slope of the BEMFsignal crossing substantially zero.

Those skilled in the art will appreciate that a control circuit forcontrolling a linear vibration motor may comprise:

a first circuit, such as for example circuits 112 and/or 114, configuredto form a first cycle of a drive signal to control a drive frequency ofa drive current through the linear vibration motor to cause a vibrationof the linear vibration motor, the drive current having a first phase;

a second circuit, such as for example circuit 221 and/or 241 and 204/orpart of 110, configured to receive a first back EMF (BEMF) signal fromthe linear vibration motor in response to a non-conducting portion ofthe first cycle of the drive signal, the second circuit configured tooperate in one of an open loop run mode or a closed loop run mode toform the drive signal wherein the control circuit is configured toadjust the drive frequency to a second frequency that is substantially afrequency of the vibration of the linear vibration motor in the closedloop run mode; and

the control circuit configured to form a second cycle of the drivecurrent with a second phase that is opposite to the first phase to slowthe vibration of the linear vibration motor wherein the control circuitis configured to receive a second BEMF signal from the linear vibrationmotor in response to non-conducting portions of the second cycle, thecontrol circuit configured to selectively enable the second circuit tomeasure another frequency of the vibration of the linear vibration motorin response to one of a positive slope or a negative slope of the secondBEMF signal and to adjust a frequency of the second cycle to a thirdfrequency that is substantially the another frequency of the vibrationof the linear vibration motor, and the control circuit configured toselectively enable the second circuit to determine if an intensity ofthe vibration is less than a vibration threshold value in response to adifferent one of the positive slope or the negative slope of the secondBEMF signal.

In another embodiment, the control circuit may also include a comparatorthat may be configured to selectively operate as a non-hysteresiscomparator in response to the control circuit selectively enabling thesecond circuit to measure the frequency of the vibration of the linearvibration motor and to selectively operate as a hysteresis comparator inresponse to the control circuit selectively enabling the second circuitto determine if the intensity of the vibration is less than a vibrationthreshold value.

An embodiment may include that the second circuit may include a counterthat counts time intervals of the second cycle and wherein the secondcircuit is configured to determine if a count value of the counter isgreater than a count threshold value in response to an output of thecomparator.

In an embodiment, the second circuit may include a counter that countstime intervals of the second cycle and wherein the second circuit isconfigured to determine if a count value of the counter is greater thana count threshold value in response to a transition of the comparatorafter one of a substantially zero crossing or modified substantiallyzero crossing of the second BEMF signal.

In another embodiment, the second circuit may include a resonantfrequency search circuit configured to estimate a frequency of a backEMF signal received from the linear vibration motor.

An embodiment may include that the resonant frequency search circuit maybe configured to measure a time between to two negative to positive zerocrossing transitions of the back EMF signal and estimate an eigenfrequency of the linear vibration motor.

Another embodiment may include that the control circuit may include adetector circuit configured to receive the BEMF signal from the linearvibration motor, and includes a zero crossing circuit configured todetect a substantially zero crossings or a modified zero crossing of theBEMF signal.

Those skilled in the art will appreciate that a method of forming asemiconductor device may comprise:

configuring a control circuit of the semiconductor device to form adrive signal to form a drive current at a drive frequency to and a firstphase to a linear vibration motor during one of an open loop run mode ora closed loop run mode;

configuring the control circuit to form an anti-drive signal having ananti-drive frequency and a second phase that is substantially oppositeto the first phase wherein the anti-drive signal has non-conductingportions of a cycle of the anti-drive signal; in an embodiment, thecontrol circuit may include a first circuit, such as for example circuit114, configured to form the anti-drive signal; and

configuring the control circuit to form an estimated eigen frequency ofthe linear vibration motor in response to a non-conducting portion ofthe anti-drive signal having a first slope and to adjust the anti-drivefrequency to another frequency that is substantially the estimated eigenfrequency, and configuring the control circuit to determine if avibration of the linear vibration motor is less than a thresholdvibration value in response to a non-conducting portion having a secondslope that is opposite to the first slope and to terminate forming theanti-drive signal.

Another embodiment of the method may include configuring the controlcircuit to receive a BEMF signal from the linear vibration motor duringthe non-conducting portions and form a first signal that isrepresentative of the BEMF signal, and configuring a comparator toreceive the first signal configuring the control circuit to selectivelyenable the comparator to operate as a non-hysteresis comparator inresponse to the first slope and to selectively operate as a hysteresiscomparator in response to the second slope.

An embodiment may include configuring the control circuit to form anestimated eigen frequency of the linear vibration motor in response to anon-conducting portion of the drive signal and to adjust the drivefrequency to a second drive frequency that is substantially theestimated eigen frequency during the closed loop run mode.

The method may have an embodiment that includes configuring the controlcircuit to selectively enable adjusting the drive frequency tosubstantially the estimated eigen frequency for a first number of cyclesof the drive signal.

Another embodiment may include configuring the control circuit to formthe drive frequency at a substantially fixed frequency for a secondnumber of cycles of the drive signal after expiration of the firstnumber of cycles.

An embodiment may include configuring a counter to count cycles of thedrive signal to determine the first and second number of drive cycles.

The method may have an embodiment that may include configuring thecontrol circuit to determine if the vibration of the linear vibrationmotor is less than a threshold vibration value includes configuring acounter to count intervals of the anti-drive signal and configuring thecontrol circuit to determine if a count value of the counter is greaterthan a count threshold value in response to the second slope.

FIG. 12 schematically illustrates an example of an embodiment of aportion of a drive control circuit 300 that may be configured to controlLRA 102. Circuit 300, in some embodiments, may be an alternateembodiment of circuit 100 (FIG. 1) or circuit 200 of FIG. 4 or circuit230 of FIG. 7. Circuit 300 may be configured to operate in the resonantsearch mode and to adjust the frequency of drive signal 201 to besubstantially the same as or near to the estimated eigen frequency ofLRA 102. Circuit 300 includes a resonant frequency search circuit thatmay be similar to the resonant frequency search circuit of any ofcircuits 100 or 200 or 230. For example, the resonant frequency searchcircuit of circuit 300 may include circuits 111, 115, 116, 117, 119, and135 and the connections thereto. In some embodiments, circuit 300 alsomay include an additional summing circuit 303 and a limiter circuit 308.Circuits 303 and 308 may also be included in some alternate embodimentsof circuits 100, 200, and/or 230. Circuit 300 may have an embodimentthat may include comparator 241, or alternately may include comparator241 and the connections thereto. Circuit 300 may also have an embodimentthat may include circuit 235 and the connections thereto and may alsoinclude circuit 239 and the connections thereto.

Circuit 300 may include an embodiment that limits the maximum andminimum values by which the drive frequency or anti-drive frequency ofdrive signal 201 may be adjusted when operating in the resonantfrequency search mode. Such as for example, may limit the maximumincrease or decrease of the frequency of signal 201 for a cycle ofsignal 201, such as for example during operation of the resonantfrequency search mode, to a frequency change limit. In one example, thefrequency change limit may be a change of plus or minus fifty percent ofthe frequency of the last cycle of signal 201. Circuit 300 may have anembodiment that may limit the change in the frequency of signal 201 foreach cycle of signal 201, for example may limit the change from thefrequency used in the previous cycle, or alternately from the initialfrequency, even if the new frequency is not the same as the estimatedeigen frequency of LRA 102. One embodiment of circuit 300 may includethat in the resonant frequency search mode, a limiter function may limitthe new calculated frequency or adjusted frequency for signal 201 to bewithin a first percentage value of a starting frequency used for signal201. In another example of an embodiment of circuit 300, the resonantfrequency search circuit may include a limiter circuit that may beconfigured to limit a change in the frequency of signal 201 to be withina range of approximately fifty percent (50%) less than or greater thanthe previous frequency, even if it causes an abnormal frequency forsignal 201.

Circuit 300 may include an embodiment that uses a first drive frequencyin response to circuit 300 beginning operation to form a first drivesignal to form a first cycle of current 123 and to start vibrating LRA102. For example, circuit 135 may form an initial value of the startingfrequency for signal 201. Circuit 300 may be configured to measure theeigen frequency of LRA 102 resulting from that first cycle of drivesignal 201 and form a new value to use for the next frequency for thenext cycle where the new value results in a frequency that issubstantially the estimated eigen frequency or near to the estimatedeigen frequency. In an embodiment, that new value may be formed assummation of the values of the outputs of circuits 117 and 119. That newvalue may be provided to limiter circuit 308. Circuit 308 may beconfigured to control the maximum increase and/or the maximum decreaseof the next frequency to a respective percent increase and/or percentdecrease of the previous frequency of drive signal 201 and form alimited-value for the new value. That limited-value resulting from thelimitation is used to form the frequency for the next cycle of drivesignal 201 and current 123. Thus, the change from the frequency of theprevious cycle may be limited to the percent increase and/or percentdecrease formed by circuit 308.

FIG. 13 illustrates in a general manner a flowchart 312 of an example ofan embodiment of a method of limiting the maximum and minimum changes ofthe drive frequency. Circuit 300 may include an embodiment that may beconfigured to operate according to the steps illustrated in chart 312.At a step 313 circuit 300 may be configured to set an initial frequencyto form the frequency for the first cycle of current 123 and drive LRA102 with the resulting current 123. At a step 314 circuit 300 may beconfigured to use the resonant frequency search mode to form theestimated eigen frequency for LRA 102. At a step 315 the percent changein the drive frequency of the previous cycle of current 123 may belimited to be within the range for a frequency change limit. Forexample, LRA 102 may have already been vibrating and the estimated eigenfrequency formed by circuit 300 may be either greater than or less thanthe frequency change limit. If the estimated eigen frequency is withinthe frequency change limit, the estimated eigen frequency may be used toform the limited-value so that the next cycle will have a frequency ofsubstantially the estimated eigen frequency as illustrated at a step317. At a step 316 circuit 300 may be configured to form the next cycleof signal 201 and current 123 using the limited-value of the frequency.

FIG. 14 schematically illustrates an example of an embodiment of blockdiagram of a circuit 325 that may be used to control the maximum andminimum changes that may be applied to the frequency of drive signal201. The elements of circuit 325 may be a portion of an embodiment ofcircuit 300.

Circuit 135 may set an initial value of frequency for the first cycle ofsignal 201 and current 123. In an embodiment this initial value maybeset into latch circuits 111, 119 and into circuit 308 so that circuit308 may store the value of the frequency used for the first cycle.During that first cycle, circuits 130/140/142, latch circuit 115 anddifference circuit 116 may detect the eigen frequency of LRA 102 andform the estimated eigen frequency. The estimated eigen frequency may bereceived by circuit 308. Circuit 308 may determine a difference betweenthe estimated eigen frequency and the frequency of the last cycle ofcurrent 123 and limit the new frequency for the next cycle of current123 to be within the frequency change limit. For example, circuit 308may subtract the value of the estimated eigen frequency from the valueof the frequency of the last cycle and determine if the result is withinthe frequency change limit. If the new value is not within the frequencychange limit, circuit 308 may be configured to form the limited-value tobe at the maximum or alternately the minimum of the frequency changelimit. If the new value of the estimated eigen frequency is within thefrequency change limit, the new value may be used for the limited-value.Circuit 119 may receive the limited-value from circuit 308. Circuit 119may, in an embodiment, store the limited value until the proper time topass the limited-value to counter 112 to set the frequency for the nextcycle of signal 201 and current 123. For example circuit 119 may passthe limited value to circuit 111, and circuit 111 may select the valuefrom circuit 119 and pass that value to circuit 112.

Those skilled in the art will appreciate that limiting the amount ofchange of the frequency of the drive signal 201 and the resulting drivecurrent 123 facilitates circuit 300 forming a vibration of LRA 102 thatis more acceptable to a user of such a circuit and easier for the userto feel.

Those skilled in the art will appreciate that any of the variousembodiments of any of circuits 100, 200, 230, and/or 300 may be used inany of the other of circuits 100, 200, 230, and/or 300.

In order to facilitate this operation, an output of circuit 116, oralternately circuit 117, may be connected to an input of circuit 303.Another input of circuit 303 may be connected to latch 119. An output ofcircuit 303 may be connected to a first input of circuit 308. A secondinput of circuit 308 may be connected to the output of latch 119. Athird input of circuit 308 may be connected to receive the initial valuefrom circuit 135. An output of circuit 308 may be connected to an inputof latch 119 so that latch 119 may receive the limited value.

FIG. 15 illustrates an enlarged plan view of a portion of an embodimentof a semiconductor device or integrated circuit 900 that is formed on asemiconductor die 901. In an embodiment, any one of circuits 100, 200,230, and or 300 may be formed on die 901. Die 901 may also include othercircuits that are not shown in FIG. 15 for simplicity of the drawing.The circuit and device or integrated circuit 900 may be formed on die901 by semiconductor manufacturing techniques that are well known tothose skilled in the art. In one embodiment, at least one of circuits100, 200, 230, and or 300 may formed in a package along with an LRA suchas LRA 201.

Those skilled in the art will appreciate that an embodiment of a controlcircuit to control a linear vibration motor, the control circuit maycomprise:

a first circuit, such as for example circuit 112 and/or 113, may beconfigured to form a drive signal to control a drive frequency of adrive current through the linear vibration motor to cause a vibration ofthe linear vibration motor, the drive current having a first phase;

a second circuit, such as for example circuit 115 and/or circuit 116and/or circuit 117 and/or circuit 119, may be coupled to the firstcircuit, the second circuit configured to receive a first back EMF(BEMF) signal from the linear vibration motor in response to anon-conducting portion of a cycle of the drive signal, the secondcircuit configured to operate in one of an open loop run mode or aclosed loop run mode to form the drive signal wherein the controlcircuit is configured to adjust the drive frequency to a secondfrequency; and

a third circuit, such as for example circuit 308, coupled to the secondcircuit to limit the second frequency to be within a first percent ofthe drive frequency.

Another embodiment of the control circuit may include that the secondcircuit may include a limiter circuit coupled to receive a digitalsignal having a first digital word representing a value of the secondfrequency wherein the limiter circuit is configured to limit a value ofthe first digital word to be within the first percent of a seconddigital word representing a value of the drive frequency.

In an embodiment, the second circuit may be configured to form ananti-drive signal having an anti-drive frequency and a second phase thatis substantially opposite to the first phase, the anti-drive signalhaving a-conducting portion and a conducting portion, the second controlcircuit configured to form an estimated eigen frequency of the linearvibration motor in response to a non-conducting portion of theanti-drive signal having a first slope and to adjust the anti-drivefrequency to another frequency that is substantially the estimated eigenfrequency, and configuring the control circuit to determine if avibration of the linear vibration motor is less than a thresholdvibration value in response to a non-conducting portion having a secondslope that is opposite to the first slope and to terminate forming theanti-drive signal.

The control circuit may have an embodiment that may include a comparatorthat may be configured to selectively operate as a hysteresis comparatorin response to the control circuit operating to determine a vibrationintensity of the linear vibration motor and to selectively operate as anon-hysteresis comparator in response to the control circuit operatingto form the estimated eigen frequency.

An embodiment may include that the control circuit may be configured toselectively enable adjusting the drive frequency to substantially anestimated eigen frequency for a first number of cycles of the drivesignal and to subsequently form the drive frequency at a fixed frequencyfor a second number of cycles.

In an embodiment, the first percent of the drive frequency may be plusor minus fifty percent (50%).

An embodiment may include that the third circuit (308) may be configuredto form the second frequency to be no greater than the first percentmore than the drive frequency or the first percent less than the drivefrequency.

Another embodiment may include that the second circuit may include aresonant frequency search circuit configured to estimate a frequency ofa back EMF signal received from the linear vibration motor.

In an embodiment, the resonant frequency search circuit may beconfigured to measure a time between to two negative to positive zerocrossing transitions of the BEMF signal and estimate the eigen frequencyof the linear vibration motor.

An embodiment of the control circuit may include a detector circuitconfigured to receive the BEMF signal from the linear vibration motor,and includes a zero crossing circuit configured to detect substantiallyzero crossings of the BEMF signal.

Those skilled in the art will appreciate that a method of forming acontrol circuit may comprise:

configuring a first circuit, such as for example circuit 204 oralternately circuit 111 and/or 115 and/or 116 and/or 117, to selectivelyoperate in one of a closed loop run mode or an open loop run mode andform a drive current at a drive frequency with a first phase to cause alinear vibration motor to vibrate, including configuring the controlcircuit to selectively estimate an eigen frequency of the linearvibration motor, and to selectively adjust the drive frequency to asecond frequency;

configuring a second circuit, such as for example circuit 308, to limita maximum value and a minimum value of the second frequency to be withina first percent of the drive frequency.

Another embodiment of the method may include configuring a thirdcircuit, such as for example circuit 239 and/or 221 and/or 241, toreceive a back EMF (BEMF) signal from the linear vibration motor and toselectively determine an eigen frequency of the linear vibration motor.

An embodiment may also include configuring the first circuit (112) toselectively form the estimated eigen frequency of the linear vibrationmotor in response to a non-conducting portion of the BEMF signal havinga first slope.

The method may have an embodiment that may include configuring thesecond circuit to form an anti-drive signal having an anti-drivefrequency with a second phase that is substantially opposite to thefirst phase wherein the anti-drive signal has non-conducting portions.

Another embodiment may include configuring the second circuit toselectively determine the eigen frequency of the linear vibration motorduring one of a positive slope or a negative slope of a firstnon-conducting portion, and to selectively determine an intensity of avibration of the linear vibration motor during a different one of thepositive slope or the negative slope of a second non-conducting portionand terminate forming the drive current in response to the vibrationdecreasing to a threshold value.

An embodiment may include configuring a counter to count intervals ofthe anti-drive signal and configuring the control circuit to determineif a count value of the counter is greater than a count threshold valuein response to the second non-conducting portion.

In an embodiment, the method may include configuring the control circuitto adjust the anti-drive frequency to a second anti-drive frequency thatis substantially the estimated eigen frequency the one of the positiveslope or the negative slope of the first non-conducting portion.

An embodiment may include configuring the control circuit to selectivelyoperate a comparator as a hysteresis comparator in response to thedifferent one of the positive slope or the negative slope of the secondnon-conducting portion.

Another embodiment may include configuring the control circuit toselectively operate the comparator as a non-hysteresis comparator inresponse to the one of the positive slope or the negative slope of thefirst non-conducting portion.

The method may also have an embodiment that may include configuring acounter to count cycles of the drive current to determine a number ofdrive cycles.

An example of an embodiment of a semiconductor device having a circuitmay comprise:

a first circuit configured to form a drive signal to form a drivecurrent to a linear vibration motor;

an output configured to receive a BEMF signal from the linear vibrationmotor;

a second circuit coupled to the receive a signal that is representativeof the BEMF signal and to form an estimate of an eigen frequency of thelinear vibration motor;

the first circuit configured to form the drive signal at a drivefrequency and a first phase and to adjust the drive frequency to a firstfrequency that is substantially the estimate of the eigen frequency ofthe linear vibration motor; and

a stop control circuit configured to form an anti-drive signal at ananti-drive frequency and a second phase that is substantially oppositeto the first phase, wherein the first circuit adjusts the anti-drivefrequency of the anti-drive signal to another frequency that issubstantially the estimate of the eigen frequency of the linearvibration motor.

In view of all of the above, it is evident that a novel device andmethod is disclosed. Included, among other features, is forming acontrol circuit to control the LRA to operate in a closed loop run mode,followed by an open loop run mode, and a break mode where in thefrequency of the signal in the break mode is adjusted. Using the openloop run mode for a portion of the time that the LRA is driven tovibrate assist in minimizing the chance that the weight with the case ofthe LRA thereby reducing audible noise. Additionally, operating in theopen loop run mode reduces the circuitry of a control circuit therebyminimizing cost. Using adjusting the frequency of the anti-drive signalin the break mode assist in operating the break mode with a frequencythat is near to the design frequency of the LRA which may reduce theamount of time required to stop the vibration of the LRA. Usingalternate sloped portions of the BEMF signal in the sync-brake modefacilitates operating the brake mode to both operate with the resonantfrequency search operation and to also determine if the vibration of theLRA has substantially stopped. Configuring the comparator to selectivelyoperate as a comparator having a hysteresis input or as a non-hysteresiscomparator facilitates Forming the control circuit to limit the changesof the drive frequency to be within the frequency change limit assistsin improving the feel of the vibrations of the LRA to a user of thesystem that includes the control circuit.

While the subject matter of the descriptions are described with specificpreferred embodiments and example embodiments, the foregoing drawingsand descriptions thereof depict only typical and non-limiting examplesof embodiments of the subject matter and are not therefore to beconsidered to be limiting of its scope, it is evident that manyalternatives and variations will be apparent to those skilled in theart. As will be appreciated by those skilled in the art, the exampleform of circuits 100, 200, 230, 300 and 325 are used as a vehicle toexplain the operation method of the brake mode and the sync-brake modeand the sequence of a method that operates the in a closed loop runmode, followed by an open loop run mode, followed by the break mode orthe sync-brake mode wherein the frequency of the anti-drive signal isadjusted, and to explain example embodiments of limiting the change ofthe drive frequency to be within the frequency change limit. Thoseskilled in the art will appreciate that the circuitry that implementsthe method may have different embodiments than the circuitry of detectorcircuit 130, circuit 140, the detailed circuitry arrangement of circuits110, 200, 230, 300, and 325.

As the claims hereinafter reflect, inventive aspects may lie in lessthan all features of a single foregoing disclosed embodiment. Thus, thehereinafter expressed claims are hereby expressly incorporated into thisDetailed Description of the Drawings, with each claim standing on itsown as a separate embodiment of an invention. Furthermore, while someembodiments described herein include some but not other featuresincluded in other embodiments, combinations of features of differentembodiments are meant to be within the scope of the invention, and formdifferent embodiments, as would be understood by those skilled in theart.

The invention claimed is:
 1. A control circuit to control a linearvibration motor, the control circuit comprising: a first circuitconfigured to form a drive signal to control a drive frequency of adrive current through the linear vibration motor to cause a vibration ofthe linear vibration motor, the drive current having a first phase; asecond circuit coupled to the first circuit, the second circuitconfigured to receive a first back EMF (BEMF) signal from the linearvibration motor in response to a non-conducting portion of a cycle ofthe drive signal, the second circuit configured to operate in one of anopen loop run mode or a closed loop run mode to form the drive signalwherein the control circuit is configured to adjust the drive frequencyto a second frequency; and a third circuit coupled to the second circuitto limit the second frequency to be within a first percent of the drivefrequency.
 2. The control circuit of claim 1 wherein the second circuitincludes a limiter circuit coupled to receive a digital signal having afirst digital word representing a value of the second frequency whereinthe limiter circuit is configured to limit a value of the first digitalword to be within the first percent of a second digital wordrepresenting a value of the drive frequency.
 3. The control circuit ofclaim 1 wherein the second circuit is configured to form an anti-drivesignal having an anti-drive frequency and a second phase that issubstantially opposite to the first phase, the anti-drive signal havinga-conducting portion and a conducting portion, the second controlcircuit configured to form an estimated eigen frequency of the linearvibration motor in response to a non-conducting portion of theanti-drive signal having a first slope and to adjust the anti-drivefrequency to another frequency that is substantially the estimated eigenfrequency, and configuring the control circuit to determine if avibration of the linear vibration motor is less than a thresholdvibration value in response to a non-conducting portion having a secondslope that is opposite to the first slope and to terminate forming theanti-drive signal.
 4. The control circuit of claim 3 further including acomparator configured to selectively operate as a hysteresis comparatorin response to the control circuit operating to determine a vibrationintensity of the linear vibration motor and to selectively operate as anon-hysteresis comparator in response to the control circuit operatingto form the estimated eigen frequency.
 5. The control circuit of claim 1wherein the control circuit is configured to selectively enableadjusting the drive frequency to substantially an estimated eigenfrequency for a first number of cycles of the drive signal and tosubsequently form the drive frequency at a fixed frequency for a secondnumber of cycles.
 6. The control circuit of claim 1 wherein the firstpercent of the drive frequency is plus or minus fifty percent (50%). 7.The control circuit of claim 1 wherein the third circuit is configuredto form the second frequency to be no greater than the first percentmore than the drive frequency or the first percent less than the drivefrequency.
 8. The control circuit of claim 1 wherein the second circuitincludes a resonant frequency search circuit configured to estimate afrequency of a back EMF signal received from the linear vibration motor.9. The control circuit of claim 1 wherein the resonant frequency searchcircuit is configured to measure a time between to two negative topositive zero crossing transitions of the BEMF signal and estimate theeigen frequency of the linear vibration motor.
 10. The control circuitof claim 1 wherein the control circuit includes a detector circuitconfigured to receive the BEMF signal from the linear vibration motor,and includes a zero crossing circuit configured to detect substantiallyzero crossings of the BEMF signal.
 11. A method of forming a controlcircuit comprising: configuring a first circuit to selectively operatein one of a closed loop run mode or an open loop run mode and form adrive current at a drive frequency with a first phase to cause a linearvibration motor to vibrate, including configuring the control circuit toselectively estimate an eigen frequency of the linear vibration motor,and to selectively adjust the drive frequency to a second frequency;configuring a second circuit to limit a maximum value and a minimumvalue of the second frequency to be within a first percent of the drivefrequency.
 12. The method of claim 11 further including configuring athird circuit to receive a back EMF (BEMF) signal from the linearvibration motor and to selectively determine an eigen frequency of thelinear vibration motor.
 13. The method of claim 12 further includingconfiguring the first circuit to selectively form the estimated eigenfrequency of the linear vibration motor in response to a non-conductingportion of the BEMF signal having a first slope.
 14. The method of claim11 including configuring the second circuit to form an anti-drive signalhaving an anti-drive frequency with a second phase that is substantiallyopposite to the first phase wherein the anti-drive signal hasnon-conducting portions.
 15. The method of claim 14 includingconfiguring the second circuit to selectively determine the eigenfrequency of the linear vibration motor during one of a positive slopeor a negative slope of a first non-conducting portion, and toselectively determine an intensity of a vibration of the linearvibration motor during a different one of the positive slope or thenegative slope of a second non-conducting portion and terminate formingthe drive current in response to the vibration decreasing to a thresholdvalue.
 16. The method of claim 15 wherein configuring the controlcircuit to determine if the vibration of the linear vibration motor isless than a threshold vibration value includes configuring a counter tocount intervals of the anti-drive signal and configuring the controlcircuit to determine if a count value of the counter is greater than acount threshold value in response to the second non-conducting portion.17. The method of claim 15 further including configuring the controlcircuit to adjust the anti-drive frequency to a second anti-drivefrequency that is substantially the estimated eigen frequency the one ofthe positive slope or the negative slope of the first non-conductingportion.
 18. The method of claim 15 further including configuring thecontrol circuit to selectively operate a comparator as a hysteresiscomparator in response to the different one of the positive slope or thenegative slope of the second non-conducting portion.
 19. The method ofclaim 18 further including configuring the control circuit toselectively operate the comparator as a non-hysteresis comparator inresponse to the one of the positive slope or the negative slope of thefirst non-conducting portion.
 20. The method of claim 11 furtherincluding configuring a counter to count cycles of the drive current todetermine a number of drive cycles.